Tetralone naphthol

The most important process to produce 1-naphthalenol was developed by Union Carbide and subsequently sold to Rhc ne-Poulenc. It is the oxidation of tetralin, l,2,3,4-tetrahydronaphthalene/719-64-2] in the presence of a transition-metal catalyst, presumably to l-tetralol—1-tetralone by way of the 1-hydroperoxide, and dehydrogenation of the intermediate ie, l-tetralol to 1-tetralone and aromatization of 1-tetralone to 1-naphthalenol, using a noble-metal catalyst (58). 1-Naphthol production in the Western world is around 15 x 10 t/yr, with the United States as the largest producer (52). 

Naphthol 1 is initially protonated at a carbon center of high electron density (C-2 or C-4). The cationic species 3 thus formed is stabilized by resonance it can add a bisulfite anion at C-3. The addition product can tautomerize to give the more stable tetralone sulfonate 4 the tetralone carbonyl group is then attacked by a nucleophilic amine (e.g. ammonia). Subsequent dehydration leads to the cation... 

The conversion of tetralin to a-tetralone may be achieved under aqueous biphasic conditions in the presence of 02, using NiCl2 as a catalyst, as shown in Scheme 9.3 [7], It is necessary to use tetraethylene pentamine (TEPA) as a surface-active ligand, as well as an emulsifier, dodecyl sodium sulfate. Some alcohol and naphthol by-products were also observed, and a radical chain mechanism has been proposed for this reaction. 

For gas chromatography analysis, samples were spiked with 2-methyl-naphthalene as an internal standard. Samples were analyzed using a Shimadzu GC-17A series gas chromatograph equipped with RTX-5 column, 15 m (length) 0.25 mm (i.d.) and 0.25 pm (film thickness). The initial column temperature was 70 °C and temperature was increased at 20 °C min 300 °C, and column temperature was held for 13 min. Retention times R naphthalene, 3.2 min 2-methyl-naphthalene, internal standard, 4.09 min 1-tetralone, 4.7 min menadione, 5.68 min 1-naphthol, 5.7 min 4-hydroxy-1-tetralone, 6.1 min and 2-methy 1-4-hydroxy-1-tetralone, 6.18,6.27,6.3 and 6.4 min. 

Tetralone from tetralone, alpha-naphthol, tetralin NaY Methyl acetate [241]... 

The preparation of 6-methoxy-2-naphthol is of particular interest as the starting point in many synthetic sequences. It is readily converted to 6-methoxy-2-tetralone through a Birch reduction... 

Partial reduction of naphthols was accomplished by sodium in liquid ammonia. In the absence of alcohols small amounts of 5,8-dihydro-a-naphthol or 5,8-dihydro- -naphthol were isolated. In the presence of tert-amyl alcohol, a-naphthol gave 65-85% yield of 5,8-dihydro-a-naphthol while -naphthol afforded 55-65% of -tetralone [399] Procedure 26, p. 211). Lith-... 

Tetralone has been prepared by a variety of methods, but the only practical procedures are relatively recent ones involving reduction of /9-naphthyl methyl ether with sodium and alcohol2 or with sodium and liquid ammonia,3 high-pressure catalytic hydrogenation of /9-naphthol,4 or catalytic oxidation of 2-tetralol by hydrogen transfer with ethylene.6... 

Interestingly, on briefly heating the salt 184 in an aqueous suspension, the intermediate a-tetralone 213 was isolated, and it was easily converted into the a-naphthol 204 (82KGS1184). 

In a series of papers, Koltunov, Repinskaya, and co-workers have reported the ionic hydrogenation of isomeric naphthols and dihydroxynaphthalenes with alkanes in the presence of aluminum halides. 1-Naphthol and substituted derivatives undergo regioselective reduction under mild conditions in excess alkane and aluminum halides with the involvement of various reactive intermediates to yield a-tetralone derivatives874 [Eq. (5.322)]. Byproducts are 3-, 6-, and 7-alkyl-substituted derivatives. Mechanistic studies875 with cyclohexane-di2 showed that deuterium incorporation takes place exclusively at C(4), indicating the involvement of super-electrophilic dication 263.2-Naphthol is much less reactive and complete conversion cannot be achieved.876... 

Several reports have suggested that carbo-carboxonium superelectrophiles may also be produced from phenols, naphthols, and related species, by diprotonation in superacidic media.34 For example, 1-naphthol is thought to form the distonic superelectrophile (93) with a variety of acids (excess AICI3, HF-SbFs, and HUSY zeolite).343 In the presence of benzene, the substituted tetralone, and with cyclohexane, 1-tetralone is produced (eq 34). 

The a- and p-tetralones are also oxidized to 2-hydroxy-1,4-naphthoquinone by KO, and a crown ether in 75% yield. In the absence of a crown ether, the oxidation proceeds slowly and in low yield (—10%). The a- and p naphthols are intermediates. ... 

The xanthate transfer process provides a simple and uniquely powerful route to a-tetralones, another family of important aromatic derivatives [69-71]. a-Tetralones are starting materials for the synthesis of a host of medicinally important compoimds. They are precursors to naphthalenes, naphthols, naphthylamines, and ring expansion through the Beckmann rearrangement provides access to benzazepine derivatives. The two examples in Scheme 34 illustrate, on one hand, the possibility of preparing a tetralone with a carbohydrate-derived appendage [69] and, on the other, the synthesis of a substituted naphthol 59 by aromatisation of tetralone 58 through acid... 

Give the products resulting from the following reactions (a) 2-naphthol + MCN + ZnCI, + HCl (b) anthracene + cA-butene-dioic anhydride (c) nap ht ho-1.4-quin one + hcxa-2.4-dicne follow cd by reaction with CrO (d) naphthalene + phihalic anhydride -i-AlCl followed by reaction with polyphosphoric acid and then reduction and dehydlogenation (e) 1-tetralone + benzaldehyde + NaOH in ethanol. 

Hydrogenation of 2-naphthol in the presence of palladium and an organic base like N-ethylmorpholine gives 2-tetralone (40%) other conditions for its reduction lead to other products. By means of Raney nickel and alkali, 1,6-dihydroxynaphthalene has been partially reduced to 6-hydroxy- 1-tetralone. ... 

The reaction may also be performed over a mixed-oxide catalyst at 280° and 100 atm. of ethylene, which serves as the hydrogen acceptor, as illustrated by the preparation of /3-tetralone from 1,2,3,4-tetrahydro-2-naphthol. By the same procedure, diisobutyryl, a diketone, has been prepared from the acyloin (27%). ... 

Naphthols are reduced to P-tetralones (which are presumably protected from further reaction as the corresponding enolate anions) even more readily and it is surprising to find that even 6-methoxy-2-naph-thol (65) is converted into ketone (66 Scheme 11). ° Reduction of the equilenin ketal (67) was found to be highly dependent on the choice of metal. Reduction of (67 Scheme 12) or its sodium salt by lithium in the absence of an alcohol afforded (after acid hydrolysis) equilin (68) as the major product, whereas... 

Chloro-5-methylnaphtho[l,2-c]-l,2-dithiolium chloride reacted similarly with 4-methyl-1-naphthol and with 4-methyl-1-tetralone. 

A versatile non-Friedel-Crafts approach to naphthols is provided by condensation of the toluic acid sulfoxide with substituted acrylates or methyl vinyl ketone. Sequential conjugate addition and acylation of the first formed anion leads to the tetralone. Pyrolysis leads to aromatiza-tlon by loss of sulfinic acid. 

C=0). Reuben and Samuel116 observed 170 chemical shift in compound 48 (6 = 315). Lippert et al.ni reported on 170 chemical shifts in compound 46 (8 = 340). Having compared < 170 in 2-naphthol (6 = 73), /3-tetralone (6 = 556) and the above-mentioned values we have additional evidence for the prevailing double bond character of carbon-oxygen bond in compounds 46 and 48. 

Methoxy-l-tetralone (7) is converted into 6-methoxy-l-naphthol (8) in 80% yield by bromination followed by dehydrohalogenation." The bromination was... 

Rhodium hydroxide is also effective in ring saturation of the hydrogenolysis-sensitive hydroquinone dimethyl or diphenylether . Use of Rh-on-carbon as catalyst permits hydrogenation of naphthols to decalols [equation (d)] and of tetralones to decalols [equation (e)] without hydrogenolysis of alkoxy substituents. ... 

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